1. Field of the Invention
This invention is concerned with means for providing crude oil compositions having low pour points containing a waxy crude and an effective pour depressant amount of an oil-soluble terpolymer.
2. Description of the Prior Art
Certain waxy crude oils, such as the high-pour crude oils, exhibit poor flow properties. A number of processes have been suggested in the art for dealing with such flow problems. For example, the pour point of waxy crudes has been improved by the removal of a part of the wax by solvent extraction at low temperatures, with the attendant expense of recovering the solvent, and the problem of disposing of the wax and of providing the cooling requirements which are substantial. In more recently proposed processes, wax has been removed without the use of a solvent by centrifuging a previously heated crude which has been cooled at a critically controlled and slow rate to a centrifuging temperature of around 35.degree.-55.degree. F.
Another widely practiced process involves cutting the waxy high-pour crudes with lighter fractions of hydrocarbons. This process suffers from a number of disadvantages, such as the fact that the procedure involves the use of relatively large amounts of expensive hydrocarbon solvents to transport a relatively cheap product. Furthermore, this practice also necessarily requires that the cutting hydrocarbon solvents be available in suitable quantities which in some instances is inconvenient, and also that there be a ready market for the solvents at the other end of the pipeline.
In transporting waxy crudes with high pour points by one method, heating equipment along the pipeline at frequent intervals is utilized to heat the crude and thus reduce its viscosity. Heaters employed for this purpose can be operated by withdrawing from the crudes being transported for use as fuels. As much as 5 percent of the crude may be utilized in providing the heating necessary for reducing the crude oil viscosity to a suitable value. Furthermore, most pipelines are not equipped with such heating installations. Also, there is the additional problem of contamination of the atmosphere when burning crude oils since they may be difficult to burn completely.
A principal object of this invention is to provide a crude oil composition which possesses an improved pour point and flow properties.